Pasa Fortress (Hanja: 婆娑山城), built along the ridgeline of Mount Pasa in Cheonseo-ri san 8-10 beonji, Daesin-myeon, Yeoju City, Gyeonggi Province, is rather well-preserved. With a circumference of approximately 943m, the height of the fortress wall at the tallest point is 6.25m, and 1.4m at the lowest point. This fortress is bestowed from the Fifth King of Silla Dynasty, King Pasa-Isageum of Gyeongju Park Clan (Reigned: 80CE ~ 112CE).
Two cornerstones for high pillars and a cornerstone for short-pillar remain at Dongmunji (East Gate Site; facing Cheonseo-ri) and at Nammunji (South Gate Site; facing Ipo-ri, Geumsa-myeon). Also at Dongmunji is the Ongsangmunji. Joined to the Han River, part of the fortress bursts out of the river.
From this point in the fortress, one can see all of the South Han River. Constructed during the period of the Three Kingdoms, the Augmented Survey of Geography of Joseon (revised version; 신증동국여지승람/新增東國輿地勝覽/Sinjeung dongguk yeoji seungnam) records that during the Japanese Imjin Invasion of Korea (1592), at the suggestion of Ryu Seong-ryong, Uiam and his army of Buddhist monks repaired a portion of the fortress wall that measured 1,100 paces in circumference. (A round trip of 1 hour on foot.)